hifisonix

Category: Articles

  • MC Head Amp Circuit Compendium

    Here is the new updated moving coil head amp designs compendium – updated 31 July 2019. The first file is a PDF compendium of about 28 different circuits with noise, distortion and current consumption details. All the LTspice sim files are zipped in the second file. What is immediately apparent from this is that having…

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  • How to wire-up a Dual Mono Bloc Amplifier

    A few people have asked about wiring up a dual mono amp aka dual mono bloc. In a dual mono bloc there are separate power supplies and lots of opportunity for cross channel ground loops and ordinary ‘classic’ ground loops as well. This wiring scheme addresses the situation were unbalanced connections between the source equipment…

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  • Noise in Electronic Circuits

    I’ve gathered a few articles here on noise as a go-to reference for anyone interested in the subject. These articles really focus on Johnson noise and not induced noise which is discussed in depth in the ‘Ground Loops’ post elsewhere on this site. I will update this post with new material as and when it…

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  • Amplifier History: The JBL SA-600

    The beautifully styled JBL SA-600 amplifier was launched by the James B. Lansing company in 1966, and Bart Locanthi (the designer) wrote the  technical article linked to at the bottom of this write-up in January 1967. I’ve included this in the hifisonix power amplifier library because it is one of the earliest – if not…

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  • Solid State Feedback Amplifiers: A Short History

    “Why, sometimes I’ve believed as many as six impossible things before breakfast.” ― Lewis Carroll, Alice in Wonderland     A Future Without Feedback by Martin Colloms There is no mysticism in amplifier design, just serious science. —Andrey A. Danilov Introduction You will recall from the The Theory of TIM by Matti Otala elsewhere on this site,…

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  • Technical Requirements of Phono Preamplifiers by Tomlinson Holman

    The two articles below were written in the 1970’s, nearly a decade before the arrival of the CD and the ‘perfect sound forever’ claim made by Philips. There was a lot of focus on phono amplifier performance at the time which it could be argued was triggered by the arrival of very high performance turntables…

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  • Richard Lee’s Ultra-Low Noise MC Head Amp

    This design was a development of Marshall Leach’s MC head-amp from the 1970’s and to my knowledge, Richard Lee’s implementation presented here has not been bested in terms of noise – about 280pV/rt Hz in a well implemented exemplar other than in the Hifisonix X-Altra MC/MM Phono Preamplifier. Importantly, it requires only about 12mA current…

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  • My Loudspeakers

    I bought a pair of B&W 703’s in about 2003 and they travelled with me all around Asia when I worked there as an expat for ten years. These are big loudspeakers with fantastic bass and mid-range articulation. The treble may be a little forward for some, but for Jazz, big band and rock they…

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  • The Endless Semantic Debate: Current and Voltage Feedback Amplifiers

    It seems some are still agonizing over the ‘current feedback’ versus ‘voltage feedback’ definition.  Clearly a case of people wanting to continue to flog a horse that was laid to rest five decades ago during the heyday of the analog computer, or they simply fail to grasp the CFA concept. I suspect there are an…

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  • The Tale of Two Recordings

    I thought I’d share my thoughts with you on the sound of two LP’s I recently acquired.   Many of you will have heard of the term ‘sound wars’ which has been coined to describe the relentless increase in the use of  dynamic range compression in modern recordings, a development it could be argued from the…

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